ESA’s Moonlight programme: Pioneering the path for lunar exploration (2024)(esa.int)
esa.int
ESA’s Moonlight programme: Pioneering the path for lunar exploration (2024)
https://www.esa.int/Applications/Connectivity_and_Secure_Communications/ESA_s_Moonlight_programme_Pioneering_the_path_for_lunar_exploration
23 comments
No. It is a fundamental data problem relating to sensor accuracy/precision. They are called "suicide burns" for a reason. Start the burn too late and you run out of time and smash into the ground. Start too early and you run out of fuel and smash into the ground. So you need a sensor with error bars similar to your safety window for the planned burn.
Let's say you need to start the burn within a +/-10m box to come to a stop 1 to 21m above the moon surface. You want a sensor with something at least 10m precision but preferably more like 1m. That would be the radar. But then say you have something like a GPS with +/-100m precision. Does that help? Your safe window is somewhere inside that 200m but you cannot be sure where until the radar comes online. So do you use the +/-100m info from the GPS? Do you maneuver to center yourself inside its error bars? All you can be sure of is that you are somewhere within that 200m and are 95% sure you are not within the 10m window. So you make a maneuver anyway. Are you now in any better an information position? No. You are still somewhere in the 200m box and are still very likely outside the 10m box. Heck, you might have been inside the 10m box and just moved yourself out of it. You just wasted fuel. The only logical thing to do is to ignore the GPS and wait for the better/actionable information from the radar. The GPS may give you a warm fuzzy but it doesn't actually help when you only have one shot at the burn.
(This problem is mirrored in areas like missile guidance. Running parallel sensors on a missile sounds like a good idea but in reality leads to confusion, wasted energy/range and reduced chance of getting to the target.)
Let's say you need to start the burn within a +/-10m box to come to a stop 1 to 21m above the moon surface. You want a sensor with something at least 10m precision but preferably more like 1m. That would be the radar. But then say you have something like a GPS with +/-100m precision. Does that help? Your safe window is somewhere inside that 200m but you cannot be sure where until the radar comes online. So do you use the +/-100m info from the GPS? Do you maneuver to center yourself inside its error bars? All you can be sure of is that you are somewhere within that 200m and are 95% sure you are not within the 10m window. So you make a maneuver anyway. Are you now in any better an information position? No. You are still somewhere in the 200m box and are still very likely outside the 10m box. Heck, you might have been inside the 10m box and just moved yourself out of it. You just wasted fuel. The only logical thing to do is to ignore the GPS and wait for the better/actionable information from the radar. The GPS may give you a warm fuzzy but it doesn't actually help when you only have one shot at the burn.
(This problem is mirrored in areas like missile guidance. Running parallel sensors on a missile sounds like a good idea but in reality leads to confusion, wasted energy/range and reduced chance of getting to the target.)
Not that I doubt your conclusions necessarily, but isn't this what sensor fusion is for? You can cast it as sensor "selection", which is fine, but given two sensors that show 10/1 accuracy (variance 100:1), and the estimates are consistent, I don't know why you'd expect it to have divergent results. (Am I understanding the problem here?). Your pos/alt is still measurable but with big old error bars until the precise sensors kick in.
You can only fuse sensors that are online. In the recent crashes the radar wasn't. The point is that you cannot swap out a high accuracy sensor, not when doing suicide burns with zero margin.
That's roughly my understanding.
Worth noting too that your original, pre-LPS[1] position/orientation/trajectory is coming from other sensors with their own error bars, namely your IMU and whatever information the ground can glean from radio signals.
If your LPS accuracy is better than your IMU accuracy, I don't see why it wouldn't make sense to start using it once it's available.
[1] gotta call it something and GPS doesn't really fit
Worth noting too that your original, pre-LPS[1] position/orientation/trajectory is coming from other sensors with their own error bars, namely your IMU and whatever information the ground can glean from radio signals.
If your LPS accuracy is better than your IMU accuracy, I don't see why it wouldn't make sense to start using it once it's available.
[1] gotta call it something and GPS doesn't really fit
My case was about not having radar at all. Having GPS could buy you some time and start braking already based on GPS even if the radar is still out. Yes, might burn some additional fuel but burning too late sucks harder I suppose.
Also: even tough I couldn't find anything about the navigation (or rather localization?) accuracy of the Moonlight system, I'd expect it to be better than 100m, but I have nothing to confirm or deny this.
Also: even tough I couldn't find anything about the navigation (or rather localization?) accuracy of the Moonlight system, I'd expect it to be better than 100m, but I have nothing to confirm or deny this.
I mean, kudos to ESA for already thinking about connectivity on the moon. But maybe a bit more pressing would be the launch of IRIS2, so we get at least sovereign satellite based telecommunications in Europe. It's set to launch with the first rockets in 2029 but the full budget post 2027 hasn't even been approved yet.
IRIS2 is a European Union project, not an ESA project. Different organisations, purposes, and countries.
Thats not really true. IRIS^2 is a joint project between the EUSPA and ESA
> The European Space Agency (ESA) is responsible for development and deployment of the system and the European Union Agency for the Space Programme (EUSPA) is responsible for the governmental service provision.
The ESA wants to be the "space agency" of the European Union anyways
https://en.wikipedia.org/wiki/IRIS%C2%B2
> The European Space Agency (ESA) is responsible for development and deployment of the system and the European Union Agency for the Space Programme (EUSPA) is responsible for the governmental service provision.
The ESA wants to be the "space agency" of the European Union anyways
https://en.wikipedia.org/wiki/IRIS%C2%B2
Delta-V or better the second book critical mass from Daniel Suarez.
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Honestly, pleasantly surprised that this is a European-led initiative, it’s really great to see ESA stepping up with such an ambitious project.
ESA is leading the way in a bunch of space stuff - we're not great at launchers, but the stuff we send up is top-notch.
There's Euclid, which maps out the visible sky in insane detail [0]
There's Galileo, which provides much higher accuracy than GPS. (20cm vs 5m!)
And then there's Copernicus, which provides open-access Earth Observation as a public good.
[0] https://www.youtube.com/watch?v=86ZCsUfgLRQ
There's Euclid, which maps out the visible sky in insane detail [0]
There's Galileo, which provides much higher accuracy than GPS. (20cm vs 5m!)
And then there's Copernicus, which provides open-access Earth Observation as a public good.
[0] https://www.youtube.com/watch?v=86ZCsUfgLRQ
>There's Galileo, which provides much higher accuracy than GPS. (20cm vs 5m!)
Very ironic name for a group of satellites orbiting the earth.
Very ironic name for a group of satellites orbiting the earth.
Mostly European. The ESA map has a little cutout for the one non-european "cooperator" state on the council.
https://www.esa.int/About_Us/Corporate_news/Member_States_Co...
https://www.esa.int/About_Us/Corporate_news/Member_States_Co...
Canada is currently pretending to be a European country sssh
We'll annex them before the Americans do!
For Canada we can rename the EU to just "the Union" or even "The United States" :)
I mean it sounds great for materials extraction, but I’m a bit skeptical on infrastructure that will make long-term exploration and a lunar economy actually viable
The Moonlight programme is one of those low-key projects that could end up being essential. Reliable navigation and comms around the Moon turns exploration into long-term infrastructure. It's less about planting flags, more about making the Moon actually usable.
For recent landers also didn't really know where exactly they landed, only after getting spotted in images taken from orbit